Chip type directional coupler

Abstract

Disclosed herein is a chip type directional coupler comprising a laminated structure having two stripline electrode substrates, each provided with a quarter-wavelength stripline electrode portion meandered on one major surface thereof, which are so stacked as to electromagnetically couple the stripline electrodes with each other and two ground electrode substrates, provided with ground electrodes, which are stacked to hold the two stripline electrode substrates, and a plurality of external electrodes formed on side surfaces of the laminated structure. Respective end portions of the stripline electrodes and the ground electrodes are electrically connected to different ones of the external electrodes respectively.

What is claimed is: 
     
       1. A chip type directional coupler comprising: a laminated structure comprising a plurality dielectric sheets including:   two dielectric substrates, each being provided with a curved quarter-wavelength stripline electrode on one major surface thereof, each said stripline electrode being located in said laminated structure so as to electromagnetically couple said stripline electrodes with each other, and   two substrates each being provided with a ground electrode on at least one major surface thereof, being stacked on both sides of said two dielectric substrates; and   a plurality of external electrodes formed on side surfaces of said laminated structure, respective end portions of said stripline electrodes and said ground electrodes being electrically connected to different ones of said external electrodes,   wherein said plurality of dielectric sheets comprise at least one additional dielectric sheet disposed between a stripline electrode and a ground electrode.   
     
     
       2. A chip type directional coupler in accordance with claim 1, wherein said laminated structure comprises a co-fired sintered body prepared by stacking a plurality of ceramic green sheets for forming said dielectric substrates and said substrates provided with said ground electrodes and firing the laminate. 
     
     
       3. A chip type directional coupler in accordance with claim 2, wherein said ground electrodes are so sized as to cover said quarter-wavelength stripline electrodes as viewed along the perpendicular direction of said laminated structure. 
     
     
       4. A chip type directional coupler in accordance with claim 2, wherein said stripline electrodes formed on said two dielectric substrates are connected to external electrodes on different side surfaces of said laminated structure. 
     
     
       5. A chip type directional coupler in accordance with claim 2, wherein said curved stripline electrodes are substantially U-shaped. 
     
     
       6. A chip type directional coupler in accordance with claim 2, wherein said laminated structure further comprises protective substrates arranged on outer sides of said two substrates provided with ground electrodes. 
     
     
       7. A chip type directional coupler in accordance with claim 1, wherein said ground electrodes are so sized as to cover said quarter-wavelength stripline electrodes as viewed along the perpendicular direction of said laminated structure. 
     
     
       8. A chip type directional coupler in accordance with claim 1, wherein said stripline electrodes formed on said two dielectric substrates are connected to external electrodes on different side surfaces of said laminated structure. 
     
     
       9. A chip type directional coupler in accordance with claim 1, wherein said curved stripline electrodes are substantially U-shaped. 
     
     
       10. A chip type directional coupler in accordance with claim 1, wherein said laminated structure further comprises protective substrates arranged on outer sides of said two substrates provided with said ground electrodes. 
     
     
       11. A chip type directional coupler in accordance with claim 1, wherein said dielectric substrates are made of ceramics. 
     
     
       12. A chip type directional coupler in accordance with claim 1, wherein at least one additional dielectric sheet is disposed between each said stripline electrode and a respective ground electrode. 
     
     
       13. A chip type directional coupler in accordance with claim 12, wherein a plurality of additional dielectric sheets are disposed between each said stripline electrode and said respective ground electrode. 
     
     
       14. A chip type directional coupler in accordance with claim 13, wherein said plurality of additional dielectric sheets has a predetermined thickness which is selected so as to provide said chip type directional coupler with a desired characteristic. 
     
     
       15. A chip type directional coupler comprising: a laminated structure comprising a plurality of dielectric ceramic sheets including:   two dielectric substrates, each being provided with a curved quarter-wavelength stripline electrode on one major surface thereof, said curved electrodes being located in said laminated structure as to electromagnetically couple said stripline electrodes with each other, and   two substrates each being provided with a ground electrode on at least one major surface thereof, being stacked on both sides of said two dielectric substrates; and   a plurality of external electrodes formed on side surfaces of said laminated structure, respective end portions of said stripline electrodes and said ground electrodes being electrically connected to different ones of said external electrodes;   wherein said plurality of dielectric ceramic sheets includes a plurality of additional dielectric ceramic sheets disposed between each said stripline electrode and a respective ground electrode.   
     
     
       16. A chip type directional coupler in accordance with claim 15, wherein said plurality of additional dielectric sheets has a predetermined thickness which is selected so as to provide said chip type directional coupler with a desired characteristic.